Ep 8. Crushing It

Hiccup, Astrid, Snotlout, Ruffnut, and Tuffnut are on their journey as they have arrived at a new island that they suspect is the location of the precious Flightmare dragon. Hiccup suspects that they aren't the only ones on the island who are after the Flightmare, and he directs Toothless to fly over with a bit of caution. While flying, Toothless receives a stunning shock from something, resulting in his fire being extinguished, but he manages to keep his balance and land safely.

The riders soon realize that the reason for Toothless's fire being put out is because he was shocked by a Thunderdrum, a dragon who has a mighty blast of sound that can shatter ice. The riders escape, and they return to their base to replenish their weapons to defeat the Thunderdrum. The group receives an alert from the Edge tower, where they learn that the dragon hunters have secretly landed on the island they previously visited. The riders decide to go back to the island and investigate the suspicious activities of the dragon hunters.

The group returns to the island, and Snotlout decides to prove that he is the best dragon rider. To show off, he attempts to catch a Thunderdrum with his weapons, but he fails miserably and lands at the edge of a cliff, where he gets trapped under a boulder. The other riders continue their search for the Dragon Hunters but rescue Snotlout when the sound from their dragon call awakens the Thunderdrum nearby, and they decide to retreat.

The riders find an abandoned Dragon Hunter campsite on the island, and they find out that the Dragon Hunter named Viggo is after the Flightmare. While exploring the campsite, Hiccup and Astrid discover that the Dragon Hunters have crushed rocks to make a thunder-proof sound barrier around the area presumed to be the Flightmare's habitat. This has left the wild Thunderdrums furious as the sound barrier blocks their migration path, and Hiccup guesses that the barrier may have led to a severe depletion in the dragon's population too.

Deciding to take the mission into their own hands, the riders plan to remove the barrier and defeat the Dragon Hunters. They sneak into the camp and begin their mission by taking on the Dragon Hunters one by one. While trying to take out the barrier, the group gets attacked by a group of Dragon Hunters, and Tuffnut and Ruffnut get captured.

With the help of their dragons, Hiccup and Astrid devise a plan to rescue their fellow riders and remove the sound barrier, which also ends up freeing the Thunderdrums. But while removing the wall, they discover the Dragon Hunters have rigged the structure with explosives. Hiccup and Toothless, with the help of Astrid, manage to dodge the explosives and take out the hunters.

In the end, the riders destroy the sound barrier and free the Thunderdrums. They also succeed in saving the Flightmare from the Dragon Hunters, who was hiding nearby the barrier all along. Viggo escapes in the chaos, but the riders manage to learn more about him before he gets away. The episode closes with the group vowing to stop the Dragon Hunters from hunting down any more dragons and setting their sights on the next mission.